The present invention relates, in general, to semiconductor devices and, more particularly, to power semiconductor devices.
Power semiconductor devices are well known and are used in many applications including automotive electronics, portable electronics, power supplies, and telecommunications. Manufacturers of these devices typically use a thick field oxide together with diffused field limiting rings and channel stop regions to reduce device leakage, reduce undesirable parasitic effects, and to enhance device breakdown. All of these approaches serve to address the same basic problem of maximum electric field relaxation of a planar junction. Each termination approach possesses a set of innate advantages and disadvantages, and the designer attempts to minimize the negative aspects of an approach while simultaneously exploiting the positive aspects. Among these approaches, field-limiting rings are one of the least costly in regards to semiconductor device manufacturing investment, as the same diffusion step used to form the PN junction of the main device can often be used to form the field-limiting rings.
Another device characteristic that semiconductor device manufacturers try to optimize is the on-resistance of the semiconductor devices. The value of this parameter is governed by the concentration of dopant in the semiconductor material in which the semiconductor device is fabricated as well as the thickness of this material. Since it is desirable to have a low on-resistance, it is preferable that the semiconductor material be thin and heavily doped.
Accordingly, it would be advantageous to have a semiconductor device and method for its manufacture that includes a termination structure and is designed to have a high breakdown voltage and a small on-resistance. It would be of further advantage for the method of manufacture to be cost efficient and integrable with available processing techniques.